"You can take any image and break it down into its core fundamental components meaningful to the visual system," Cole tells Shots. "This would be things like luminance, contrast, wavelength of light."

When they performed their analysis, they found that images that evoked the phobic reaction to holes had quite unique characteristics in terms of contrast and levels of fine details.

But why would that particular characteristic make people's skin crawl? The answer came to Cole one day when he was visited by a man who said he suffered from trypophobia. In the course of their conversation, the man revealed he had a phobic reaction every time he looked at a blue-ringed octopus.

Not knowing anything about blue-ringed octopuses, Cole called up some Web images while his visitor was there. One thing Cole learned from his search was that blue-ringed octopuses are extremely venomous.

And that gave him an idea. He searched for images of other venomous animals, and once he had found several, he showed them to his visitor. "He couldn't look at the images," says Cole, because they elicited the same phobic response as an image of holes.

So Cole decided to analyze the images of the venomous animals and found that they had the same unique characteristics as the trypophobic images he had already analyzed.

What does this mean? Cole speculates that when someone with trypophobia sees an image or object with holes in it, it stimulates a primitive portion of his or her brain that associates the image with something dangerous. He says you can think of it as a kind of unconscious reflex reaction that happens faster than the conscious brain can say, "There's nothing to worry about."

In other words, trypophobia may be the remnants of an evolutionary adaptation that made total sense: If you see a venomous animal, get scared and move away as quickly as possible.